<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <style>
        .d1{
            border: 1px solid red;
            width: 100px;
            height: 100px;
            background: black;
        }
        .c2{
            border: 1px dashed red;
            height: 100px;
            width: 100px;
        }
        .c3{
            border: 5px double green;
            height: 100px;
            width: 100px;
        }
        .c4{
            border: 20px groove fuchsia;
            height: 100px;
            width: 100px;
        }
    </style>
</head>
<body>
    <div class="d1"></div>
        <br>
    <div class="c2"></div>
        <br>
    <div class="c3"></div>
        <br>
    <div class="c4"></div>
</body>
</html>